A truss is understood to comprise a plurality of parallel tubes, bars, rods or other straight members held spaced apart at various points along the length of each of the members in order to form a stronger structural member than each member would be individually. For fabrication or other reasons, the trusses have lengths which are usually shorter than a span across which they are to extend. Consequently, it is necessary to connect trusses end to end and, also, to connect end trusses to structural walls or other such items. The almost universal mechanism for making such a connection is to bolt one truss to another or to bolt the truss to a structural wall. Nut and bolt connections are positive, and structural adequacy is easily verified. The disadvantage with nut and bolt connections is that they are time consuming to accomplish and, consequently, expensive.
A space frame commonly includes a plurality of nodes and tubes in various arrangements depending on the application. Space frames are used to support roofs, walkways, scaffolding, and often provide modern looking structural support in architecturally pleasant buildings such as halls, churches, office buildings, etc. More particularly, a space frame is usually constructed by a single tube extending between a pair of nodes. Each node has a plurality of faces and can receive a tube at each face. Therefore, it is common for a number of tubes to be attached to a single node so that a complex, but usually uniform, pattern is formed.
Representative connecting devices are shown in a number of patents. For example, U.S. Pat. No. 2,149,844 shows a sleeve device into which one or more tubes may be inserted and welded. U.S. Pat. No. 4,343,562 shows a somewhat different structure but also utilizes the concept of inserting a tubular member into a core member and welding the two. Other patents show different concepts. For example, U.S. Pat. No. 3,914,060 shows a node member having a plurality of studs with sleeves attached thereto for threading onto ends of tubular sections. U.S. Pat. No. 4,023,913 shows a connector having socket-like ends over which tubular members fit. U.S. Pat. No. 4,313,687 shows a node having a plurality of threaded openings, each of which are for receiving a bolt retained to an end of a tube. A pair of threaded bodies attached to the bolt function to tighten the tube to the node. Other commercial systems are available which actually have a threaded rod fixed at the end of a tube for threading into a threaded opening in a node. Finally, still a different concept is shown in U.S. Pat. No. 4,340,318 wherein a node connection includes a plurality of half joints having semicircular tongue and groove elements with tubes having similar tongue and groove elements mating therewith. Locking latches are provided to keep the halves from separating.
Some of these various connectors are less complex than others, and some are less expensive to make and use. In general, however, various presently known connectors require a significant amount of work time to complete the connection. That is, a welder must weld, or a laborer must thread one piece to another. U.S. Pat. No. 4,340,318 perhaps requires a lesser amount of assembly time, but likely is fairly expensive to manufacture due to the complex design of the tongue and groove assembly and the locking latch assembly.
Thus, although numerous connecting assemblies are known, there continues to be a need for improvements which will simplify and make less expensive without decreasing structural strength or reliability. In this regard, the present invention advances connector art significantly.